Weight gain commonly occurs in women following the diagnosis of breast cancer. Post-diagnosis weight gain may increase risk for recurrence, and obesity at diagnosis of breast cancer is an established negative prognostic factor. Weight control is of great concern to many breast cancer survivors. Post-diagnosis weight gain is positively associated with energy intake and inversely related to physical activity level, suggest that behavioral strategies to reduce energy intake or increase exercise are likely to influence the long-term pattern of weight gain. Newer behavioral skills training programs to promote the adoption and maintenance of physical activity based on social learning theory have demonstrated success in other groups of inactive adults. Also, we have demonstrated than an intensive, innovative telephone-based counseling intervention can promote major changes in the dietary intakes for women at risk for breast cancer recurrence. The hypothesis to be tested in this exploratory project is that telephone-based counseling can also be useful in facilitating the adoption and maintenance of increased physical activity, and thus, promote weight loss in overweight and obese breast cancer survivors. One approach to healthy weight management emphasizes increased physical activity, improved body image, self- acceptance, and healthy eating attitudes and behaviors. The core content of the curriculum to be used in this project is based on a behavioral skills training program that has been shown to be effective in other target groups of inactive adults, with the incorporation of cognitive-behavioral techniques and emotional processing to promote acceptance and address the unique needs and characteristics of breast cancer survivors. The specific aims of this study are: (1) To examine the effect of a group- based program to increase physical activity and promote healthy eating attitudes and behaviors on measured weight change at the end of an intensive treatment period (16 weeks) and at one year, compared to a wait-list control group; (2) To examine the additional effect of individualized telephone counseling to increase physical activity and promote healthy eating attitudes and behaviors on measured weight change at the end of an intensive treatment period (16 weeks) and at one year, compared to the control group; and (3) To collect preliminary data on the change in level of physical activity that may be expected to occur in breast cancer survivors who participate in a group-based program and individualized telephone counseling to promote healthy weight management.